Proof That Crash Training Doesn't Work

Several hard workouts in three weeks caused runners' fitness to decline.

A new study backs nine-time New York City Marathon champion Grete Waitz's advice about the best way to progress as a runner: Hurry slowly.

In the study, when runners did 24 hard workouts over an eight-week period, their fitness improved throughout, and they peaked with a 10% increase in VO2 max, a measure of aerobic capacity. In contrast, when runners did the same 24 hard workouts in a three-week period, their fitness declined during the training block, and improved only after almost two weeks of no running.

The full Waitz quote is, "Hurry slowly. Be dedicated and disciplined and work hard, but take your time. Move ahead, but be patient."

That counsel might be hard to accept when, for whatever reason, an important race is imminent and you're not in the shape you'd hoped to be. In such situations, it's tempting to think that crash training will do the job.

Sorry, but not so fast, the study found. As described above, Norwegian researchers divided runners into two groups, what we'll call the sane-training group and the crash-training group. The workout they all did 24 times was 4 x 4:00 hard, with a 3:00 recovery jog, at 90% to 95% of VO2 max, an effort level that roughly corresponds to a little slower than 5K race pace. All of the workouts were done running uphill on a treadmill. (So maybe the two groups should be insane-training group and really-insane-training group.)

At the beginning of the study, the runners were of similar fitness, as measured by VO2 max. After the sane-training group had done eight of the hard workouts, their VO2 max improved 2.3%, and after 16 of the 24 hard workouts, their VO2 max had improved 7.1%. The crash trainers, in contrast, showed almost no improvement after eight hard workouts, and a slight decline in VO2 max after 16.

"Our results show that the highly intensified training load experienced by the [crash-training] group was too severe to progressively adapt compared to the [sane-training group] program," the researchers wrote. Granted, the crash-training group's program was extreme even for crash training, with an average of more than one hard workout per day for three weeks. But most runners who have tried to cram too many hard sessions into a short time would agree with the point about not being able to adapt.

The study also found that, even in the sane-training group, the full benefits of their training were available only after they stopped doing the hard workouts.

After their last hard workout, both groups stopped running entirely. Four days later, the sane-training group recorded their highest VO2 max values, an average improvement of 10.7% over their pre-study fitness. Four days after their last hard workout, the crash-training group still showed no improvement, presumably because of lingering fatigue. The crash trainers finally showed improvement 12 (non-running) days after their last hard workout. Even then, their improvement was 6.1%, less than the sane trainers experienced after 16 of the 24 workouts.

Overall, it's fair to say the crash trainers got much less return for their efforts than the sane trainers.

That the sane trainers' VO2 max peaked after four days of rest is consistent with most good training programs, which schedule the last hard workout before an important race four to seven days before. The study's version of a taper–no running at all–is unlikely to work for most regular runners. Most good coaches advise short, easy runs during that time, with a light turnover session, such as striders or 200-meter repeats, one or two days before to maintain a feeling of sharpness.